CBSE 12TH BIOLOGY - Online Test
Q1. Which of the following are difficult to explain in terms of natural selection?
Answer : Option A
Explaination / Solution:
All the traits that appear due to natural selection do not have adaptive value. This concept is although true but cannot be explained in terms of natural selection.
Q2. _______ involve the transfer of embryo at 8-celled stage in the fallopian tube of female.
Answer : Option C
Explaination / Solution:
The transfer of embryo at 8-celled stage in the fallopian tube of female is called ZIFT (zygote intra fallopian transfer). During test tube baby programme egg fertilized in vitro is transferred to fallopian tube for further growth and development.
Q3.
Assertion: Genetic map up of an organism or individual lies in the DNA sequence.
Reason: If two individual differs, then their DNA sequence should also be different.
Answer : Option C
Explaination / Solution:
DNA sequencing is the process of determining the precise order of nucleotides within a DNA molecule. It includes any method or technology that is used to determine the order of the four bases—adenine, guanine, cytosine, and thymine—in a strand of DNA.
Genetic map up of an organism or individual lies in the DNA sequence. If two individual differs, then their DNA sequence should also be different.
Q4. Enzyme produced by mammalian sperm for entry into ovum is
Answer : Option C
Explaination / Solution:
Mammalian sperm acrosome contains enzyme hyaluronidase that break down the Zona pellucida layer of ovum for fertilisation. Acrosome is present at the tips of sperm.
Q5. The process in which heritable variations enabling better survival are enabled to reproduce and leave greater number of progeny is called
Answer : Option B
Explaination / Solution:
Natural selection is the process whereby organisms better adapted to their environment tend to survive and produce more offspring. The theory of its action was first fully expounded by Charles Darwin, and it is now regarded as be the main process that brings about evolution.
Q6. Exponential growth is maximum in
Answer : Option D
Explaination / Solution:
Exponential growth is maximum in tissue culture because each cell divides continuously to form callus of cells. Sufficient amount of nutrient is also available in culture media.
Q7. Rice genome projects includes
a. Fingerprinting of HindIII and Eco RI.
b. Assembly of the fingerprinted BACs into contigs.
a. Fingerprinting of HindIII and Eco RI.
b. Assembly of the fingerprinted BACs into contigs.
Answer : Option A
Explaination / Solution:
The Rice genome projects involves fingerprinting of HindIII and EcoRI BAC libraries, assembling the fingerprinted BACs into contigs, anchoring of the BACs onto the physical map with DNA gel restriction fragment length polymorphism (RFLP) and BAC end sequence analysis, and connecting and extending of contigs by chromosome walking.
Q8. Physical and chemical changes in the egg cortex which occur after the sperm entry into the egg is called
Answer : Option B
Explaination / Solution:
After the entry of sperm into the egg the zona pellucida layer undergoes physical changes that prevent the entry of addition sperm. This reaction between zona pellucida is called cortical reaction.
Q9.
Assertion- Evolution is a continuous process that takes millions of years for speciation.
Reason- During evolution small variation accumulates guided by natural selection that leads to speciation.
Answer : Option D
Explaination / Solution:
Evolution is a slow and continuous process that takes long time to form a new species. Variation due to mutation, genetic drift, geographical isolation leads to speciation.
Q10. Which of the following is not a cause of male sterility?
Answer : Option B
Explaination / Solution:
Male sterility is mainly due to less number of sperm count or sperms motility is very less to fertile the ovum. The first case is called oligospermia and second case is called azoospermia. Tubal infertility is present in female.
